递归-汉诺塔

可以用递归实现，递归算法：

A source tower,B buffer tower ,C destination tower
1. Move the subtree consisting of the top n-1 disks from A to B.
2. Move the remaining (largest) disk from A to C.
3. Move the subtree from B to C.

Base Case：How do you move a subtree of two disks from A to C? Move the subtree consisting of only one disk (1) from A to B. This is the base case: When you’re moving only one disk, you just move it; there’s nothing else to do. Then move the larger disk (2) from A to C, and replace the subtree (disk 1) on it.

从A移动到C的过程如下：

柱子数据结构：用栈实现

class Tower{  pirvate Stack diskStack;  private int index; //the current tower's index in the Towers arrary  public Tower(i){    diskStack=new Stack();index=i;  }    public void add(int d){    if(!diskStack.isEmpty() && diskStack.peek()<=d){   System.out.println("Error placing disk " +d);}else   diskStack.push(d);  }//end add    public int getIndex(){   return index;  }//end getIndex()}//end class Tower

汉诺塔代码

public static void main(String[] args){   int diskNumber=5; //disks number   int towerNumber=3; //tower number       Tower[] towers=new Tower[3];   //initial tower's index in the towers' array   for(int i=0;i<3;i++)     towers[i]=new Tower(i);   //initial towers[0]   for(int i=diskNumber-1;i>=0;i--)     towers[0].add(i);    //move disk from 0 to 2   moveDisks(n,towers[0],towers[1],towers[2]);  }//end mainpublic static moveDisks(int n,Tower from,Tower buffer,Tower to){  if(n==1)  //base case    moveTop(from,to);  else{    moveDisks(n-1,from,to,buffer);  //from A to BmoveTop(from,to);//from A to CmoveDisks(n-1,buffer,from,to);//from B to C  }//end else}//end moveDisks()private static moveTop(Tower from,Tower to){   int top=from.pop();    to.add(top);   System.out.println("Move disk "+top+" from "+ from.getIndex()+" to "+ to.getIndex() );}//end moveTop()